This project has been undertaken to detect and characterize RNA and/or DNA oncogenic viruses in human prostatic cancer, and to determine the significance of any detected viruses or viral genetic information in the origin of this type of cancer. Ultrastructural studies demonstrated virus-like particles in some prostate carcinoma specimens and in one case of benign prostate hyperplasia. Both mature and budding forms of virus particles have been observed and resemble type C virus particles, associated with tumors in a variety of animal species. Immunological studies revealed the presence of antibodies in sera of the majority of patients which react with cytoplasmic antigens of cells derived from prostate cancer. Some of the sera react with cells from cervical carcinoma. The nature of this cross-reactivity is now under study. Sera from 55 normal donors were negative. The results suggest that these antibodies are directed specifically against tumor cell-associated antigens. Biochemical studies initiated to detect oncogenic virus genetic information in prostatic cancer cells suggest that prostatic carcinoma and benign hyperplastic tissue as well as normal prostatic tissue contain gene sequences related to those of known RNA tumor viruses. This similarity between genetic information in the cells of prostatic tissues and nucleic acid of a mammalian tumor virus is now under study. This project is designed to gain information on the causes of prostatic cancer as an approach to additional means of management of this neoplastic disease.